1. Field of the Invention
The present invention relates to a withdrawable interlock device of a vacuum circuit breaker, and more particularly, to a withdrawable interlock device of a vacuum circuit breaker for controlling the withdrawal of a circuit breaker body according to whether or not a control power plug is coupled to a control power connector.
2. Description of the Related Art
In general, a circuit breaker is an electrical protection device for protecting a load device or line from a fault current when an accident occurs such as a short circuit, a ground fault or the like generated from an electrical circuit.
Such a circuit breaker may be divided into an oil circuit breaker using an oil as an extinguishing medium, a gas circuit breaker using sulphur hexafluoride (SR6) gas which is an inert gas, an air circuit breaker using the air as an extinguishing medium, a circuit breaker using magnetic attraction, a vacuum circuit breaker using the dielectric strength of the vacuum, and the like, according to the extinguishing medium.
In recent years, most power device products have used sulphur hexafluoride gas having an excellent arc-extinguishing and insulation performance as an insulation medium, but the use of sulphur hexafluoride gas has been regulated throughout the world since its greenhouse effect is 23,900 times higher than that of carbon dioxide.
The development of eco-friendly power device products that would be able to replace sulphur hexafluoride gas have been actively carried out in the domestic market, and as one of the eco-friendly power device products, the demand of vacuum circuit breakers has been increased.
The vacuum circuit breaker takes mostly charge of the role of power transfer control and power system protection, and has a large breaking capacity and high reliability and stability as well as is able to be mounted even in a small installation space, and thus its application range has been extended from medium voltage to high voltage.
Here, the vacuum circuit breaker may be installed along with a switchgear in which various electrical devices including a circuit breaker are placed and managed for the operation or control of a power plant, a substation and the like, the operation of a motor or the like, and accommodated and used within a cradle fixed to the switchboard.
The vacuum circuit breaker may be divided into a fixed type and a withdrawable type, and the withdrawable circuit breaker may be divided into a disconnecting position at which both the main circuit and control circuit of the vacuum circuit breaker are separated therefrom, a test position at which the main circuit is separated therefrom but the control circuit is connected thereto, and a connecting position at which both the main circuit and control circuit are connected thereto, according to the extent of the vacuum circuit breaker being withdrawn into or from the cradle.
Here, the circuit breaker body receives an electrical signal while moving to the connecting position from the test position to be turned on or off, wherein a control power plug is provided in the circuit breaker body, and a control power connector is provided within a switchboard provided with the circuit breaker body, and thus control power is applied to or blocked from the circuit breaker body according to whether or not the control power plug is coupled to the control power connector.
On the other hand, FIG. 1 is a perspective view illustrating a circuit breaker body, and FIG. 2 is a schematic diagram illustrating a circuit breaker body located within the cradle prior to being withdrawn into the switchboard in a state that the control power plug is separated from the control power connector, and FIG. 3 is a schematic diagram illustrating a state in which a circuit breaker body located within the cradle is withdrawn into the switchboard in a state that the control power plug is coupled to the control power connector, and FIG. 4 is a perspective view illustrating a carriage for moving a circuit breaker body within the cradle.
As illustrated in FIGS. 1 through 4, a vacuum circuit breaker in the related art may include a switchboard 40, a cradle 30 inserted into the switchboard 40, a circuit breaker body 10 moving within the cradle 30, a carriage 20 on which the circuit breaker body 10 is mounted to move within the cradle 30, and the like.
A control power plug 41 configured to provide power is provided within the switchboard 40, and a control power connector 11 detachably connected to the control power plug 41 is provided in the circuit breaker body 10.
According to the foregoing configuration, when the circuit breaker body 10 moves to a connecting position from a test position while moving within the cradle 30 in a state that the circuit breaker body 10 is mounted on the carriage 20, the control power plug 41 and control power connector 11 moves to a connecting position in a state that they are connected to each other.
Here, a load terminal and a busbar terminal provided in the circuit breaker body 10 may be connected to a terminal of the cradle 30 while the circuit breaker body 10 moves within the cradle 30 through the carriage 20, thereby completing the movement to a connecting position.
However, according to a vacuum circuit breaker having the foregoing configuration in the related art, the circuit breaker body 10 may be separated from the outside of the switchboard 40 in a state that control power is supplied to the circuit breaker body 10 without any additional configuration for preventing the circuit breaker body 10 from being separated out of the switchboard 40 from a test position at which the control power connector 11 is coupled to the control power plug 41, thereby resulting in the occurrence of an accident for the operator or the damage of the vacuum circuit breaker.